AU2005318227B2

AU2005318227B2 - Stereoselective process and crystalline forms of a camptothecin

Info

Publication number: AU2005318227B2
Application number: AU2005318227A
Authority: AU
Inventors: Marco Alpegiani; Walter Cabri; Paolo Carminati; Paolo Ghetti; Fabrizio Giorgi; Mauro Marzi; Maria Ornella Tinti; Domenico Vergani
Original assignee: Sigma Tau Industrie Farmaceutiche Riunite SpA
Current assignee: Sigma Tau Industrie Farmaceutiche Riunite SpA
Priority date: 2004-12-21
Filing date: 2005-12-16
Publication date: 2011-08-18
Anticipated expiration: 2025-12-16
Also published as: JP5491699B2; BRPI0515832A; WO2006067092A2; EP1828196B1; SI1828196T1; KR101355121B1; HRP20120926T1; US20100311783A1; PL1828196T3; CA2590756A1; JP2013067629A; AU2005318227A1; ME01495B; CY1117243T1; US20100311784A1; CN101084221A; EP1828196A2; DK1828196T3; CN101084221B; KR20070097535A

Abstract

A stereoselective process for preparing 7-[(E)-t-butyloxyiminomethyl]- camptothecin (also known as gimatecan) is herein disclosed. With the addition of further dissolution and precipitation steps carried out in appropriate different solvent mixtures, four new crystalline forms of gimatecan are also obtainable by using the same stereoselective process.

Description

WO 2006/067092 PCT/EP2005/056849 1 STEREOSELECTIVE PROCESS AND CRYSTALLINE FORMS OF A CAMPTOTHECIN Field of the Invention This invention relates to a stereoselective process for preparing 7-[(E) t-butyloxyiminomethyl] -camptothecin (also known as gimatecan). With the addition of further dissolution and precipitation steps carried out in appropriate different solvent mixtures, three new crystalline forms of gimatecan are obtainable by using the same stereoselective process Background of the Invention Camptothecin is an alkaloid, which was isolated by Wall et al (J. Am. Chem. Soc. 88, 3888-3890 (1966)) for the first time from the tree Camptoteca acuminata, a plant originating from China, of the Nys saceae family. The molecule consists of a pentacyclic structure having a lactone in the E ring, which is essential for cytotoxicity. The drug demonstrated a wide spectrum of antitumor activity, in particular against colon tumors, other solid tumors and leukemias, and the first clinical trials were performed in the early 70's. Since Camptothecin (CPT) has low water solubility and in order to prepare clinical trials, the National Cancer Institute (NCI) prepared the sodium salt (NSC100880), which is water-soluble. Clinical trials in phase I and II were not completed because of the high toxicity showed by the compound (hemorrhagic cystitis, gastrointestinal toxicity, such as nausea, vomit, diarrhoea, and myelosuppression, especially leuco penia and thrombocytopenia. Subsequently, many CPT analogues were synthesised in order to ob tain compounds with lower toxicity and higher water solubility. Two drugs are marketed, irinotecan (CPT-11) (CamptosarTM by Upjohn) and topotecan (HycamtinTM or ThycantinTM by Smith Kline & Beecham).

WO 2006/067092 PCT/EP2005/056849 2 All the derivatives identified to-date contain the parent structure with 5 rings, essential for cytotoxicity. It was demonstrated that modifica tions on the first ring, such as in the case of the above-mentioned drugs increase water solubility and allow a higher tolerability of the drug. Patent application W097/31003 discloses derivatives of camptothecins substituted at positions 7, 9 and 10. Position 7 provides the following substitutions: -CN, -CH(CN)-R 4 , -CH=C(CN)-R 4 , -CH 2

-CH=C(CN)-R

4 , C(=NOH)-NH 2 , -CH=C(N0 2

)-R

4 , -CH(CH 2

NO

2

)-R

4 , 5-tetrazolyl, 2- (4, 5-dihydroxazolyl), 1,2 ,4-oxadiazolidin-3-yl- 5-one, wherein R 4 is hy drogen, linear or branched alkyl from 1 to 6 carbon atoms, nitrile, car boxyalkoxy. Of these compounds, the best one proved to be the 7-nitrile (7-CN), hereinafter named CPT 83, with cytotoxic activity on non-small cells lung carcinoma (non-SCLC, H-460). This tumour line is intrinsically resistant to cytotoxic therapy and is only moderately responsive to to poisomerase I inhibitors, notwithstanding the overexpression of the target enzyme. CPT 83 is more active than topotecan, taken as refer ence compound and on the whole it offers a better pharmacological pro file, even in terms of tolerability, then a better therapeutic index. CPT 83 is prepared trough a synthesis route comprising the oxidation of 7-hydroxymethylcamptothecin to camptothecin 7-aldehyde, the transformation of the latter into oxime and final conversion into ni trile. The starting compound and the intermediates are disclosed in Sawada et al., Chem. Pharm. Bull., 39, 5272 (1991). This paper makes refer ence to a patent family with priority of 1981, for example European patent application EP 0056692, published in 1982. In these publica tions camptothecin 7-aldehyde and its oxime are described among oth ers.

WO 2006/067092 PCT/EP2005/056849 3 The usefulness of these derivatives is to provide compounds with anti tumor activity having low toxicity starting from 7 hydroxymetylcamptothecin. In the paper published on Chem. Pharm. Bull. 39, 5272 (1991), the authors demonstrate that, with respect to camptothecin, the 7-alkyl and 7-acyloxymethyl derivatives, which were not foreseen in the above mentioned patent application, are the more active compounds on lines of murine leukemia L1210, while lower ac tivity, always with respect to camptothecin, was observed in com pounds bearing 7-substitutions with high polar character, such as hy drazones and the oxime - CH(=NOH). In patent application EP1044977 and in Dallavalle S. et al., J. Med. Chem. 2001, 44, 3264-3274, camptothecin derivatives are described which bear an alkyloxime O-substituted at position 7 and which are endowed with antitumor activity higher than the compound of refer ence topotecan. Moreover these camptothecin derivatives bearing an imino group on position 7, also show an improved therapeutic index. Among these compounds one of the preferred molecules was shown to be 7-t-butoxyiminomethylcamptothecin (CPT 184). When this molecule is prepared as described in EP1044977 and in the above Dallavalle pa per, a mixture of the two E and Z isomers, in 8:2 ratio, is obtained from a solvent mixture containing ethanol and pyridine. All the processes described in the above-mentioned literature for ob taining camptothecin derivatives bearing alkyloxime O-substituted at position 7 lead to a mixture of the two E and Z isomers of the oxime or the alkyloxime. Therefore, it is desirable to make available a stereoselective process leading to single E,Z isomers, respectively, more particularly the E isomer. Many drugs, old and new, were discovered and rushed into market as their 'suitable' crystalline forms and had never been screened thor oughly for their potential polymorphic forms. With the recent techno- WO 2006/067092 PCT/EP2005/056849 4 logical advancement of solid state chemistry, it is possible that new po lymorphic forms can be discovered, which have never been seen before. The new polymorphic forms are often able to deliver therapeutic ad vantages and represent one of the new challenges of the pharmaceuti cal industry. As a matter of fact polymorphism, the ability of a mole cule to crystallize into more than one crystal arrangement, can have a profound effect on the shelf life, solubility, formulation properties, and processing properties of a drug. More seriously, the action of a drug can be affected by the polymorphism of the drug molecules. Different polymorphs can have different rates of uptake in the body, leading to lower or higher biological activity than desired. In extreme cases, an undesired polymorph can even be toxic. The occurrence of an unknown polymorphic form during manufacture can have an enormous impact on a drug company. Therefore it is vital that researchers involved in the formulation of crystalline products be able to select the polymorph with the correct properties and anticipate problems such as the un wanted crystallization of other polymorphs. Surprisingly, a very large number of pharmaceuticals exhibit the phenomenon of polymorphism. 70% of barbiturates, 60% of sulfonamides and 23% of steroids exist in different polymorphic forms. The problem of polymorphism in organic compounds is generically re viewed by Caira, M. R. "Crystalline Polymorphism of Organic Com pounds", Topics in Current Chemistry, Springler, Berlin, DE, Vol. 198, 1998, pages 163-208. Conducting a crystallization study on gimatecan has brought the Ap plicant to the claimed invention. Description of the Drawings Figure 1 reports on the left the structural formula of 7-[(E)-t butyloxyiminomethyl]-camptothecin (gimatecan) and on the right the formula of 7-[(Z)-t-butyloxyiminomethyl]-camptothecin.

5 Figure 2 reports X-ray diffraction pattern of the crystalline form I of 7 [(E)-t-butyloxyiminomethyl]-camptothecin (gimatecan). Figure 3 reports X-ray diffraction pattern of the crystalline form HI of 7-[(E)-t-butyloxyiminomethyl]-camptothecin (gimatecan). Figure 4 reports X-ray diffraction pattern of the crystalline form III of 7-[(E)-t-butyloxyiminomethyl]-camptothecin (gimatecan). Detailed Description 6f the Invention We have now surprisingly found a stereoselective process for preparing 7-[(E)-t-butyloxyiminomethyl]-camptothecin (also known as gi matecan). We have also found that it is possible to obtain the complete conversion of the Z isomer into the E isomer. For clarity, the structural formulae of the two isomers are shown in Figure 1. Moreover, we found that this product can exist under different crystal line forms and that these forms can be obtained by using the same stereoselective process with the addition of further dissolution and precipitation steps carried out in appropriate different solvent mix tures. Therefore in one aspect the present invention provides a process for the stereoselective preparation of 7-[(E)-t-butyloxyiminiomethyl]-campto thecin comprising reacting an acetal of 7-formyl-camptothecin with 0 t-butylhydroxylamine hydrochloride in a polar protic or aprotic organic solvent, preferably under acidic conditions (pH<7). In fact it has been found that the amount of Z isomer is proportional to the amount of base (for example pyridine) added. Therefore the process of the present invention must be carried out in the absence of an organic base, in par ticular, in the absence of pyridine. Different embodiments and variations of the above process are com prised in the present invention.

6 Preferably, the polar protic or aprotic organic solvent is an alcohol, such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i butanol. More preferably, it is ethanol or methanol. The pH is preferably acidic, but it can be brought to higher values (close but not equal to 7) with the addition of an inorganic base. Pref erably, the inorganic base is sodium or potassium hydroxide. Prefera bly, the inorganic base is added in a molar ratio of 0.5-0.9:1 with re spect to the hydroxylamine hydrochloride. The acetal of 7-formyl-camptothecin is a dialkyl acetal, preferably methyl or ethyl acetal. The temperature of the reaction is usually comprised between room temperature and solvent boiling point. At the end of the reaction the precipitate is isolated from the reaction mixture, for example by filtration. According to the process of the present invention, the E isomer is al ways obtained in a ratio of at least 95:5 with respect to the Z isomer. The Examples show that the process of the invention allows to obtain the E isomer up to a ratio of 99.8:0.2 with respect to the Z isomer. According to a preferred embodiment of the invention the above described process comprises further steps, such as dissolving the pre cipitate previously obtained in dichloromethane, adding a co-solvent, concentrating the solution obtained and crystallizing the product thus obtained. In another aspect, the present invention provides a compound obtainable by the processes of the present invention. Depending on the co-solvent used, different crystalline forms are ob tained as follows.

6A In other embodiments, the present invention provides different crystalline forms.

WO 2006/067092 PCT/EP2005/056849 7 SOLVENTS Polymorph (by IR and Polymorph (by powder X DSC) ray diffraction) Acetone I I MeOH III III EtOH III III Hexane II 75% II (with a substantial amount of amorphous) EtOAc II II Toluene II II n-Butyl chloride II II Methyl t-butyl ether II 90% II III 10% Using acetone as co-solvent, crystalline form I of gimatecan is ob tained, which is characterized by a powder X-ray diffraction pattern obtained by irradiation with CuK-a 1 X-rays, as shown in Figure 2.

WO 2006/067092 PCT/EP2005/056849 8 The characteristic main diffraction peaks of this form are given in the following table: Degrees 2-Theta Relative intensity (%) 7.2 100 9.2 4.8 10.2 7.3 12.7 16.3 14.0 8.1 14.7 9.5 15.2 13.0 16.0 2.4 16.7 4.06 19.7 3.2 20.5 3.2 20.7 4.06 22.2 6.5 26.5 3.2 32.5 2.4 Using ethanol or methanol as co-solvent, crystalline form III of gi matecan is obtained, which is characterized by a powder X-ray diffrac tion pattern obtained by irradiation with CuK-a 1 X-rays, as shown in Figure 4. The characteristic main diffraction peaks of this form are given in the following table: WO 2006/067092 PCT/EP2005/056849 9 Degrees 2-Theta Relative intensity (%) 6.0 1.0 7.5 100.0 8.51 8.1 12.3 4.8 16.0 6.0 17.0 11.0 18.0 6.6 18.2 4.0 18.7 6.0 23.2 2.4 25.2 3.6 Using ethyl acetate, toluene, n-butyl chloride, methyl t-butyl ether or hexane as co-solvent, crystalline form II of gimatecan is obtained, which is characterized by a powder X-ray diffraction pattern obtained by irradiation with CuK-a 1 X-rays, as shown in Figure 3. The charac teristic main diffraction peaks of this form are given in the following table: 10 Degres 2-Theta Relative intensity (%) 6.7 100.0 7.2 4.8 9.7 6.0 11.2 24.0 13.2 3.0 14.5 4.8 16.0 2.4 16.7 21.6 17.0 31.2 17.5 10.8 19.0 3.0 21.0 4.8 23.0 3.6 25.5 7.2 26.5 6.0 28.2 3.0 The diffraction peaks recited above for crystalline forms I, II and III of gimatecan are +O.02 degrees. In further aspects, the present invention further provides these new crystalline forms I, II and III of gimatecan. Crystalline form I of gimatecan is preferred. In another aspect, the present invention provides amorphous form I of gimatecan. In another aspect the present invention relates to a use of any crystalline form of gimatecan (especially form I, II or III), or a mixture thereof, as medicaments, in particular in the preparation of a medicament for treating pathological states which arise from or are exacerbated by cell proliferation, or for treating a tumor disease. In a further aspect, the present invention provides a method for treating a mammal suffering from a tumor disease comprising administering a therapeutically effective amount of a compound which is a crystalline form of gimatecan, or a pharmaceutical composition comprising a crystalline form of gimatecan.

10A In another aspect, the present invention provides a pharmaceutical composition comprising: (a) a compound which is a crystalline form of gimatecan; and (b) a pharmaceutically acceptable carrier or diluent; and further comprising (c) one or more pharmaceutically acceptable excipients. In a further aspect the present invention provides a composition, in particular a pharmaceutical composition, comprising at least one of the above mentioned crystalline forms as active ingredient, the pharmaceutical compositions being in admixture with at least one pharmaceutically WO 2006/067092 PCT/EP2005/056849 11 acceptable carrier and/or diluent. In addition, pharmaceutical composi tions of the present invention can contain also one or more pharmaceu tically acceptable excipients. Gimatecan shows an antiproliferative activity, therefore its crystalline forms are useful for their therapeutical activity, and possess physico chemical properties that make them suitable to be formulated in pharmaceutical compositions. The pharmaceutical compositions comprise at least one of the above mentioned crystalline forms of gimatecan, in an amount such as to produce a significant therapeutical effect, in particular antitumoral ef fect. The compositions comprised within the present invention are con ventional and are obtained with commonly used methods in the phar maceutical industry. According to the desired administration route, the compositions shall be in solid or liquid form, suitable to the oral, parenteral, intravenous route. The compositions according to the pre sent invention comprise together with the active ingredients at least a pharmaceutically acceptable vehicle or excipient. Formulation co adjuvants, for example solubilizing, dispersing, suspending, emul sionation agents can be particularly useful. The above-mentioned crystalline forms of gimatecan can also be used in combination with other active ingredients, for example other anti tumor drugs, both in separate forms, and in a single dose form. The above-mentioned crystalline forms of gimatecan according to the present invention are useful as medicaments with antitumor activity, for example in lung tumors, such as the non-small cell lung tumour, tumors of the colon-rectum, prostate, gliomas. Cytotoxic activity is assayed in cell systems of human tumour cells, us ing the antiproliferative activity test as a method of evaluation of the cytotoxic potential.

12 These and other advantages of the present invention shall be illustrated in detail also by means of the following Examples. The following examples further illustrate the invention. Introduction Example 1 and 2 deal with the synthesis of 7-[(E)-t-butyloxyiminome thyl]-camptothecin employing 7-formyl-camptothecin dimethylacetal as starting material. Examples 3 and 4 report the synthesis of 7-[(E)-t-butyloxyiminome thyl]-camptothecin employing 7-formyl-camptothecin as starting mate rial under conditions that afforded the E isomer. All the reactions of this group are faster then the reactions reported in Examples 1 and 2, indicating that hydrolysis of the acetal is plausibly slower than the re action of the aldehyde to give the oxime. Example 5 reports the conversion of the Z isomer into the E isomer. Example 6 reports the synthesis and the characterization of the differ ent (polymorphic) crystalline forms that can be obtained for 7-[(E)-t butyloxyiminomethyl]-camptothecin (gimatecan). HPLC: the analyses are carried out on an instrument equipped with a quaternary pump (Waters Alliance 2690) with automatic injector (in jected volume 5 pl) and with a UV detector operating at 260 nm (Wa ters 2487) controlled by the software Waters 'Empower Pro'. A C18 reverse phase column (Symmetry C18; 75x4.6mm Waters) is used with a linear elution gradient (see table below), with 1.0 ml/min flow rate. Gradient program A: H 2 0/CHaCN 60140 (v/v) B: H 2 0/CHaCN 30/70 (v/v) WO 2006/067092 PCT/EP2005/056849 13 Time (min) % A % B 0 100 0 30 100 0 40 0 100 45 100 0 50 100 0 The retention time of 7-[(E)-tert-butyloxyiminomethyl]-camptothecin is 12 minutes, and the retention time of the Z-isomer is 8 minutes. Example 1 Preparation of 7-[(E)-tert-butyloxviminomethyll-camptothecin from 7 formylcamptothecin-dimethylacetal 7-Formyl-camptothecin-dimethylacetal (500mg; 1.2mmol) and 0-tert butylhydroxylamine hydrochloride (372mg; 2.9mmol) were added to 95% ethanol (12.5 ml) in a three-necked flask, protected from light and equipped with a magnetic stirrer and a condenser. The mixture was heated to reflux for 4h. HPLC analysis showed a E:Z ratio 99.8:0.2. The crude product was obtained as precipitated from the reaction mix ture and isolated by filtration. After chromatographic purification on silica gel (20g), eluting with dichloromethane-methanol 95:5, gi matecan (460mg) was obtained as a yellow powder (yield: 87%). Example 2 Preparation of 7-[(E)-tert-butyloxviminomethyll-camptothecin from 7 formylcamptothecin-dimethylacetal 7-Formyl-camptothecin-dimethylacetal (500mg; 1.2mmol), 0-tert butylhydroxylamine hydrochloride (372mg; 2.9mmol) and sodium hy droxide (59mg; 1.47mmol) were added to 95% ethanol (12.5 ml) in a three-necked flask, protected from light and equipped with a magnetic stirrer and a condenser. The mixture was heated to reflux 24h. HPLC WO 2006/067092 PCT/EP2005/056849 14 analysis showed a E:Z ratio 98.8:1.2. The crude product was obtained as precipitated from the reaction mixture and isolated by filtration. Af ter chromatographic purification on silica gel (20g), eluting with di chloromethane-methanol 95:5, gimatecan was obtained as a yellow powder (yield: 80%) Example 3 (Reference example) Preparation of 7-[(E)-tert-butyloxviminomethyll-camptothecin from 7 formylcamptothecin 7-Formyl-camptothecin (500mg; 1.33mmol), O-tert-butylhydroxylami ne hydrochloride (417mg; 3.3mmol) and sodium hydroxide (67mg; 1.65mmol) were added to 95% ethanol (12.5 ml) in a three-necked flask, protected from light and equipped with a magnetic stirrer and a condenser. The mixture was heated to reflux for 2 hours. HPLC analysis showed a E:Z ratio 97.4:2.6. The crude product was obtained as precipitated from the reaction mixture and isolated by filtration. After chroma tographic purification on silica gel (20g), eluting with dichloromethane methanol 95:5, gimatecan (480mg) was obtained as a yellow powder (yield: 80%). Example 4 (Reference example) Preparation of 7-[(E)-tert-butyloxviminomethyll-camptothecin from 7 formylcamptothecin 7-Formyl-camptothecin (500mg; 1.33 mmol), O-tert-butylhydroxylami ne hydrochloride (417mg; 3.3mmol) and sodium hydroxide (120mg; 3mmol) were added to 95% ethanol (12.5 ml) in a three-necked flask, protected from light and equipped with a magnetic stirrer and a con denser.

WO 2006/067092 PCT/EP2005/056849 15 The mixture was heated to reflux for 2 hours. HPLC analysis showed a E:Z ratio 95.5. The crude product was obtained as precipitated from the reaction mixture and isolated by filtration. After chromatographic purification on silica gel (20g), eluting with dichloromethane-methanol 95:5, gimatecan (550 mg) was obtained as a yellow powder (yield: 93%). Example 5 Isomer Conversion 7-[(Z)-tert-butyloxyiminomethyl]-camptothecin (100 mg) was dissolved in dichloromethane (30 ml). Hydrochloric acid (0.2 ml) was added at room temperature and the mixture was subjected to irradiation with a 125 W Hg high pressure U.V. lamp for 1 hour. The HPLC analysis showed that Z-isomer was completely converted into the E-isomer. Example 6 Crystallization Studies 7-[(E)-tert-butyloxyiminomethyl]-camptothecin (2.5g) was dissolved in of dichloromethane (500 ml). A co-solvent (500 ml) was added to the so lution, then by means of a rotavapor, the mixture was concentrated at a temperature of 40 0 C up to a volume of 250 ml. The suspension was kept under stirring at room temperature for 30 minutes, then the solid formed was filtered by washing twice with 20 ml of the co-solvent. After one night in an oven at 50 0 C under vacuum, 2.1 g of product were obtained. The co-solvents used were the following: acetone, ethanol, methanol, ethyl acetate, toluene, n-butylchloride, methyl tert-butyl ether, and hexane.

WO 2006/067092 PCT/EP2005/056849 16 The crystals obtained were analyzed by X-ray powder Diffractometry. The diffractograms were obtained on 20-50 mg of powder by using a Siemens D-500 computer controlled diffractometer equipped with a CuK-a radiation source monochromated with (002) graphite crystals, with Sollers slits and narrow (0.3*) divergence and receiving apertures. The confidence limits of the scattering angles are ± 0.5 2-Theta. Samples obtained using acetone as co-solvent (form I) gave the fol lowing results. The X-ray powder diffractogram is characteristic of a crystalline sub stance. The characteristic main diffraction peaks of this form are given in the following table: Degrees 2-Theta Relative intensity (%) 7.2 100 9.2 4.8 10.2 7.3 12.7 16.3 14.0 8.1 14.7 19.5 15.2 13.0 16.0 2.4 16.7 4.06 19.7 3.2 20.5 3.2 20.7 4.06 22.2 6.5 26.5 3.2 32.5 2.4 Samples obtained using ethanol or methanol as co-solvent (form III) gave the following results.

WO 2006/067092 PCT/EP2005/056849 17 The X-ray powder diffractogram is characteristic of a crystalline sub stance. The characteristic main diffraction peaks of this form are given in the following table: Degrees 2-Theta Relative intensity (%) 6.0 11.0 7.5 100.0 8.5 18.1 12.3 4.8 16.0 6.0 17.0 11.0 18.0 6.6 18.2 4.0 18.7 6.0 23.2 2.4 25.2 3.6 Samples obtained using ethyl acetate, toluene, n-butyl chloride, methyl t-butyl ether or hexane as co-solvent (form II) gave the following results. The X-ray powder diffractogram is characteristic of a crystalline sub stance. The characteristic main diffraction peaks of this form are given in the following table: WO 2006/067092 PCT/EP2005/056849 18 Degrees 2-Theta Relative intensity (%) 6.7 100.0 7.2 4.8 9.7 6.0 11.2 24.0 13.2 3.0 14.5 4.8 16.0 2.4 16.7 21.6 17.0 31.2 17.5 10.8 19.0 3.0 21.0 4.8 23.0 3.6 25.5 7.2 26.5 6.0 28.2 3.0 To further characterize these crystalline forms of gimatecan, the same samples were examined by IR spectroscopy. In the following table are given the peaks (cm-1) characteristic of the three forms. Form I (acetone) Form II (AcOEt)* Form III (EtOH)** Frequency (cm-1) Frequency (cm-1) Frequency (cm-1) 1751.7 1761.7 1739.3 1606.4 1605.0 1619.8 1162.2 1156.7 1154.4 766.2 764.3 759.5 * identical data are observed also for the forms obtained from toluene, n-butyl chloride, methyl t-butyl ether or hexane ** identical data are observed also for the form obtained from methanol 19 IR spectra were collected at 4 cm- 1 on 1% KBr pellet with a Perkin Elmer Spectrum 1000 FT-JR Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

1. A process for the stereoselective preparation of 7-[(E)-t-butyloxyiminomethyll camptothecin comprising reacting in acidic conditions an acetal of 7-formyl camptothecin with 0-t-butylhydroxylamine hydrochloride in a polar protic or aprotic organic solvent.

2. The process according to claim 1, wherein the polar protic or aprotic organic solvent is an alcohol selected from the group consisting of ethanol or methanol.

3. The process according to claim 1 or 2 wherein the acetal of 7-formyl-camptothecin is a dialkyl acetal.

4. The process according to claim 3, wherein the acetal of 7-formyl-camptothecin is dimethyl or diethyl acetal.

5. The process according to any one of claims 1 to 4, wherein the reaction temperature is kept between room temperature and solvent boiling point.

6. The process according to any one of claims 1 to 5, wherein at the end of the reaction the precipitate is isolated from the reaction mixture.

7. The process according to claim 6, wherein the precipitate is isolated from the reaction mixture by filtration.

8. The process according to claim 6 or 7, further comprising dissolving the precipitate in dichloromethane, adding a co-solvent, concentrating the solution so obtained and allowing the reaction product to precipitate and crystallize.

9. The process according to claim 8, in which the co-solvent is selected among acetone, toluene, n-butyl chloride, methyl- t-butyl ether or hexane, ethyl acetate, ethanol or methanol. 21

10. A compound obtainable by the process of claim 8 or 9, which is a crystalline form of 7- [(E)-t-butyloxyiminomethyl]-camptothecin.

11. The compound of claim 10 which is crystalline form I of 7-[(E)t butyloxyiminomethyl]-camptothecin and which shows on X-ray diffraction a peak at an angle of refraction 2 theta (0), of 7.2 ± 0.2 degrees.

12. The compound according to claim 11, having an X-ray diffraction pattern, expressed in terms of 2 0 angles, that includes five or more peaks selected from the group consisting of about 10.2, 12.7, 14.0, 14.7 and 15.2 ± 0.02 degrees.

13. The compound according to claim 11 or 12, having substantially the same X-ray diffraction pattern as shown in Figure 2.

14. The compound of claim 10 which is crystalline form II of 7-[(E)-t butyloxyiminomethyl]-camptothecin and which shows on X-ray diffraction a peak at an angle of refraction 2 theta (0), of 6.7 ± 0.2 degrees.

15. The compound according to claim 14, having an X-ray diffraction pattern, expressed in terms of 2 0 angles, that includes five or more peaks selected from the group consisting of about 11.2, 16.7, 17.0, 17.5 and 25.5 ± 0.02 degrees.

16. The compound according to claim 14 or 15, having substantially the same X-ray diffraction pattern as shown in Figure 3.

17. The compound of claim 10 which is crystalline form III of 7-((E)- t butyloxyiminomethyl]-camptothecin having an X-ray diffraction pattern, expressed in terms of 2 0 angles, that shows a peak at 7.5 ± 0.2 degrees and further includes five or more peaks selected from the group consisting of about 6.0, 8.5, 17.0, 18.0 and 18.7 0.02 degrees. 22

18. The compound according to claim 17, having substantially the same X-ray diffraction pattern as shown in Figure 4.

19. A composition comprising a compound of any one of claims 10 to 18.

20. A pharmaceutical composition comprising: (a) a compound of any one of claims 10 to 18; and (b) a pharmaceutically acceptable carrier or diluent; and further comprising (c) one or more pharmaceutically acceptable excipients.

21. The pharmaceutical composition according to claim 20, which is a dosage form suitable for oral administration.

22. The pharmaceutical composition according to claim 20 or 21, wherein said dosage form is selected from a tablet, capsule or solution.

23. Use of a compound of any one of claims 10 to 18, in the preparation of a medicament for the treatment of a tumor disease.

24. Method for treating a mammal suffering from a tumor disease comprising administering a therapeutically effective amount of a compound of any one of claims 10 to 18 or pharmaceutical composition of any one of claims 20 to 22.

25. The process according to claim 1, the compound according to claim 10, the composition according to claim 19, the pharmaceutical composition according to claim 20, the use according to claim 23 or the method according to claim 24, substantially as hereinbefore described and/or exemplified.